U.S. Pat. No. 7,624,606 disclosed “rekeyable lock cylinder, plug assembly of the same and method for rekeying the same” is considered relevant to the present invention disclosing a rekeying process that is to replace a new valid key by an old one. However, this might cause inconvenience in rekeying and key management with regard to hotel having numerous rooms, new building or rental mansion. In general, hotel owner only needs to provide lodger a key for opening the lock, but if the lock cylinder of room lock is rekeyable, lodger can execute rekeying process to replace a new valid key by an old one personally, which results in inconvenience of key management. Therefore, hotel owner anticipates the valid key that lodger possesses has ability to open the lock without rekeying capability. The rekeying process is executed only by hotel owner.
Accordingly, it will be obvious to those skilled in the art that the present invention is to develop a rekeyable lock cylinder that makes valid keys match with each of the rekeyable lock cylinders separately have ability to open the lock only without rekeying capability and each of the rekeyable lock cylinders matched with respective matching keys is able to execute rekeying process via a same control key only.